Along an assembly line, various types of articles, for example sanitary napkins, diapers, and other absorbent articles, may be assembled by adding components to and/or otherwise modifying an advancing, continuous web of material. For example, in some processes, advancing webs of material are combined with other advancing webs of material. In other examples, individual components created from advancing webs of material are combined with advancing webs of material, which in turn, are then combined with other advancing webs of material. In some cases, individual components created from advancing web or webs are combined with other individual components created from other advancing web or webs. Webs of material and component parts used to manufacture diapers may include: backsheets, topsheets, leg cuffs, waist bands, absorbent core components, front and/or back ears, fastening components, and various types of elastic webs and components such as leg elastics, barrier leg cuff elastics, stretch side panels, and waist elastics. Webs of material and component parts used to manufacture sanitary napkins may include: backsheets, topsheets, secondary topsheets, absorbent core components, release paper wrappers, and the like. Once the desired component parts are assembled, the advancing web(s) and component parts are subjected to a final knife cut to separate the web(s) into discrete articles.
During the assembly process, various components and/or advancing webs of material may be bonded together in various ways. For example, in some processes, advancing webs and/or components may be bonded together with adhesives. In other processes, advancing webs and/or components may be mechanically bonded together with heat and/or pressure without the use of adhesives. An example of such a mechanical bonding method and apparatus is disclosed in U.S. Pat. No. 4,854,984, wherein two laminates are bonded together by advancing through a nip between a patterned cylinder and an anvil cylinder. Pattern elements on the patterned cylinder exert pressure on the two laminates against the anvil roll to create discrete bond sites. More particularly, bond sites are created as the extreme nip pressure compresses and yields the laminate material in areas between the pattern elements and the anvil. During the bonding process, some of the yielded material may flow from the bond site to areas surrounding the perimeter of the pattern element.
These mechanical bonding methods may damage the resultant laminate web by forming holes and/or tears in or around the bond sites. For example, pattern elements may comprise sharp edges and may tear, cut, or weaken the bonded web in areas adjacent to the bonds. Tears may propagate from one bond site to another, causing a zippering of the web. This often creates a consumer-noticeable defective product. In addition, as the web basis weight of the laminate decreases, bonds may become more susceptible to bond defects such as tearing and holes at relatively high nip pressures.
Consequently, it would be beneficial to provide a method and apparatus for mechanically bonding substrates that produces bond sites with relatively low likelihood of damage to the substrate. Previous attempts to address these problems are not desirable due to cost and complexity. There is a desire for bonding with pressure applying members which minimize the applied process strain on a substrate, so that this applied process strain is less than the failure strain of the substrate of interest. There is a need to reduce or eliminate substrate damage, such as tearing and holes, as a result of bonding.